Novel methodology to evaluate the effect of residual moisture on epoxy resin sealer/dentine interface: a pilot study.

AIM: To evaluate the sealer/dentine interface associated with an epoxy resin sealer using the combination of Goldner's trichrome stain (GTS) and scanning electron microscopy (SEM) to verify the use of the experimental methodology. METHODOLOGY: Extracted human maxillary incisors (6) were subjected to root canal treatment. Subsequent to pulp removal, canal instrumentation and smear layer removal using EDTA and NaOCl, teeth were randomly and equally assigned to a 'wet' or 'dry' group. The 'dry' group was desiccated (95% ethanol/suction/paper points/air-drying), whilst the 'wet' group was treated with a saline rinse/suction/single paper point. Canals were then filled with an epoxy-based resin sealer and warm vertical gutta-percha compaction. After 7-day storage at 37°C, roots from each group were sectioned into apical, middle and coronal horizontal subsections that were cut and split into paired halves and evaluated with GTS or SEM. With GTS sections, hybrid layer and sealer tubular penetration were measured (n=15 measurements/intracanal location/condition) and evaluated using a two-factor repeated measures analysis of variance. The SEM qualitative analysis of paired sections was included as a complementary confirmation of GTS analyses. RESULTS: In dry and wet groups, there was no conspicuous sealer/dentine interface hybrid layer, irrespective of canal location. However, dry specimens exhibited more uniform sealer distribution with deeper tubular penetration in the coronal and middle third (P<0.05). In contrast, there was decreased sealer distribution and tubule penetration in the apical third, regardless of moisture condition (P<0.05). CONCLUSIONS: The experimental methodology (combination of GTS and SEM) can be used to evaluate the intracanal resin sealer/dentine interface. The pilot data indicated that thorough drying of the root canal system may result in improved epoxy resin sealer distribution and deeper resin sealer tubular penetration, especially in the coronal and middle thirds of root canals.

Effectiveness of a prescale gel on subgingival calculus.

A prescale gel product, designed to facilitate the removal of calculus, has recently been introduced and marketed to the dental profession. The purpose of this study was to evaluate the effectiveness of this gel on the removal of subgingival calculus. 10 patients, each with 5 periodontally diseased teeth scheduled for extraction, participated in this in vivo/in vitro study. 4 teeth per patient were randomly assigned using a 2-by-2 block design and treated in vivo with either active or placebo gel, with or without scaling, prior to extraction. To assess possible overexposure to the product, 10 selected teeth from the sample were treated with active gel for an extended exposure time. Standardized scaling was performed on a 4x4 mm treated root area in vitro on groups as assigned. Quantification of residual calculus was determined by one examiner blind to treatment group assignment using SEM photomicrograph montages and the Java image analysis computer system. Repeated measures ANOVA showed no statistically significant treatment effect for gel (p > 0.05) in the scaled and no-scaled groups. The 5th group exposed to the prescale gel for an extended time was evaluated descriptively for root surface morphological changes with no noticeable effect. Based on the results of this investigation, treatment of subgingival calculus with prescale gel offers no advantage for calculus removal over scaling alone. The findings suggest no significant clinical impact of product use.